Aenictus wiwatwitayai

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Aenictus wiwatwitayai
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species: A. wiwatwitayai
Binomial name
Aenictus wiwatwitayai
Jaitrong & Yamane, 2013

This species inhabits lowland primary forests. All of Thai specimens were collected from dry evergreen forests.

Identification

A member of the ceylonicus group. Jaitrong and Yamane (2013) – Aenictus wiwatwitayai is similar to Aenictus baliensis, Aenictus longicephalus and Aenictus minipetiolus in having the mandible with more than 4 teeth and smooth and shiny propodeal dorsum. It can be separated from the latter three by the following characteristics: mesosoma almost flat dorsally or feebly convex (strongly convex in the latter); subpetiolar process low, with its anteroventral corner angular, and directed forward and downward (subpetiolar process subrectangular in the latter).

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Oriental Region: Thailand (type locality), Vietnam.


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Little is known about the biology of Aenictus wiwatwitayai. The genus is comprised of species that live an army ant lifestyle. Aenictus typically prey on other ants, from other genera, or other insects such as wasps or termites. There are reports of Aenictus preying on other insects as well and even have been observed collecting honeydew from homopterans (Santschi, 1933; Gotwald, 1995) but this appears, at least from available evidence, to be uncommon. Foraging raids can occur day or night across the ground surface. Occasionally raids are arboreal. During a raid numerous workers attack a single nest or small area, with several workers coordinating their efforts to carry large prey items back to the nest or bivouac. Aenictus have a nomadic life style, alternating between a migratory phase in which nests are temporary bivouacs in sheltered places above the ground and a stationary phase where semi-permanent underground nests are formed. During the nomadic phase bivouacs move regularly, sometimes more than once a day when larvae require large amounts of food. Individual nests usually contain up to several thousand workers, although nest fragments containing only a few hundred workers are often encountered. Queens are highly specialised and look less like workers than in most ant species. They have greatly enlarged gasters (dichthadiform) and remain flightless throughout their life. New colonies are formed by the division of existing colonies (fission) rather than by individual queens starting colonies on their own.

Castes

Known only from the worker caste.

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • wiwatwitayai. Aenictus wiwatwitayai Jaitrong & Yamane, 2013: 218, figs. 20A-C (w.) THAILAND.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

(holotype and paratypes). Larger workers (n = 10): TL 2.00–2.05 mm; HL 0.45–0.50 mm; HW 0.40–0.45 mm; SL 0.28–0.35 mm; ML 0.63–0.68 mm; PL 0.18–0.20 mm; CI 89–90; SI 69–78. Smaller worker (n = 1): TL 1.80 mm; HL 0.40 mm; HW 0.35 mm; SL 0.20 mm; ML 0.55 mm; PL 0.15 mm; CI 88; SI 57.

Head in full-face view subrectangular, clearly longer than broad, sides convex, posterior margin straight; occipital margin bearing a carina. Antennal scape relatively short, not reaching 2/3 of head length. Frontal carina relatively short, not reaching the level of posterior margin of torulus. Parafrontal ridge feeble and incomplete. Anterior clypeal margin concave, concealed by curved anterior extension of frontal carina. Masticatory margin of mandible with a large acute apical tooth followed by a medium-sized subapical tooth, 2-3 denticles, and a medium-sized basal tooth; basal margin almost straight. Maximum width of gap between anterior clypeal margin and mandibles about 2.4 times as broad as maximum width of mandible. Promesonotum weakly convex or almost straight dorsally and sloping gradually to propodeal junction; metanotal groove indistinct; mesopleuron relatively long, demarcated from metapleuron by an indistinct groove; metapleural gland bulla relatively large, its maximum diameter about 2.2 times as long as distance between propodeal spiracle and metapleural gland bulla. Propodeum in profile with almost straight or feebly convex dorsal outline; propodeal junction nearly right-angled; declivity of propodeum widely and shallowly concave, encircled with a distinct rim. Petiole slightly longer than high, its node low, dorsally convex; subpetiolar process weakly produced below, its anteroventral corner acutely angulate and ventral margin convex. Postpetiole subrectangular, shorter than petiole, with its dorsal outline almost straight.

Head including mandible and antennal scape entirely smooth and shiny. Dorsum of mesosoma smooth and shiny except for anteriormost portion and area in front of propodeal junction punctate; mesopleuron and lateral face of propodeum with relatively irregular longitudinal rugae; metapleuron largely smooth and shiny. Petiole dorsally smooth and shiny, remainder reticulate; postpetiole entirely smooth and shiny.

Head with relatively dense long standing hairs mixed with dense short hairs; mesosoma dorsally with relatively dense decumbent hairs; longest pronotal hair 0.08-0.10 mm long. Head, mesosoma, petiole, and postpetiole reddish brown; gaster and legs yellowish brown.

Smaller worker (a paratype). Similar to the larger worker in general appearance with the following conditions that should be noted: head relatively long and narrow (CI 88); antennal scape very short (SI 57), not reaching half length of head; sculpturation weaker than in the larger worker, entire body smooth and shiny.

Type Material

Holotype. THAILAND: Worker from NE. Thailand, Nakhon Ratchasima Prov., Sakaerat Environmental Research Station, dry evergreen forest, 9.VII.1999, leg. Sk. Yamane, TH99-SKY-05 (THNHM). Paratypes. Nineteen workers, same data as holotype (BMHN, MCZC, SKYC, THNHM).

Etymology

The species is named after Dr. Decha Wiwatwitaya of the Ant Museum, Faculty of Forestry, Kasetsart University, who has guided W. Jaitrong in various ways.

References